There is a rotation mechanism which includes a cover 3 constituting a cup holder body, a container restraining flap 4 rotatably supported on the cover 3 by a shaft portion (corresponding to the pivot of the present invention) 42, and a torsion coil spring 5 for urging one of the cover 3 and the flap 4 so as to rotate relative to the other, as exemplified in FIG. 9 (configuration disclosed in Patent Document 1). Here, the cover 3 has a pair of support portions 34 and shaft holes 35 coaxially provided in the support portions 34. The flap 4 has a torsion coil spring accommodating part, i.e., an accommodating space between leg parts 41, protrusions 43 each provided to face an inner surface side of each leg part 41, and the shaft portions 42 each provided on an axis of each protrusion 43 on an outer surface side of each leg portion 41. The torsion coil spring 5 has abutting portions formed by extending both end portions of a coil shape. Then, the flap 4 is rotatably coupled to both support portions 34 through the fitting of the shaft portions 42 and the shaft holes 35. The torsion coil spring 5 is disposed such that both end portions of the coil shape are held around the axes of the corresponding protrusions 43 and each abutting portion abuts against different one of the cover 3 and the flap 4.
In the case where the spring torque of the above torsion coil spring is high, the spring deformation becomes large when the flap 4 is rotated against the urging force of the torsion coil spring 5. Thus, there is a possibility that end portions of the coil shape are disengaged from the protrusions 43. As measures against this, it is also conceivable that the protrusions 43 to be fitted into the end portions of the coil shape are lengthened such that the end portions are not easily disengaged. However, when the protrusions 43 are lengthened, the torsion coil spring cannot be held around the axes of the protrusions.
As another measures, instead of a configuration in which the torsion coil spring is held by a pair of protrusions, a shaft 5 may be used to hold the torsion coil spring around the axis of the shaft and thus to prevent the detachment of the torsion coil spring, as exemplified in FIG. 10 (configuration disclosed in Patent Document 2). In FIG. 10, a reference numeral 2 indicates a grip body, reference numerals 3A and 3B indicate holding bodies (corresponding to the attachment base of the present invention) for rotatably coupling and holding the grip body 2 via the shaft 5, and reference numerals 4 and 5 indicate shafts for rotatably coupling the grip body 2 to the holding bodies 3A, 3B.